It is known that the operation of electrical machines such as generators or the like having a stator arrangement, comprising a stator having a stator yoke with a number of stator slots, with each stator slot accommodating at least one set of stator windings, and a rotor being rotatable relative to the stator is accompanied by heat losses or copper losses respectively.
In order to avoid thermal overheating which would lead to lowered efficiency or even to damage or a reduction of the lifetime, particularly the insulation lifetime of the electrical machine, usually cooling means are provided with the stator arrangement.
EP 1 499 001 A1 discloses a device for cooling an electrical machine comprising a stator in which successive recesses are provided in a circumferential direction. The recesses contain at least one winding and open out on an inlet face of the stator. Thereby, at least one cooling tube extending in the longitudinal direction of the recess is disposed in each of the stator recesses. The at least one cooling tube is located in the inlet portion of the recess closest to the air gap.
Yet, the cooling efficiency of known cooling means is often times not satisfying.